ALL-315: Outcome of Adults with Relapsed/Refractory T-Cell Acute Lymphoblastic Leukemia or Lymphoblastic Lymphoma

Abstract

Context Limited data are available on the outcome of adults with relapsed-refractory (R/R) T-cell acute lymphoblastic leukemia (ALL) or lymphoblastic lymphoma (LBL). Objective We aimed to identify factors predictive for long-term survival and to establish the benchmark for expected outcomes in this setting. Main outcomes measured We reviewed characteristics and outcome of adults with R/R T-cell ALL or LBL treated at our institution between 2009 and 2019. We assessed response to salvage therapy and overall survival. To determine prognostic factors for survival, we performed univariate and multivariate analyses using the following baseline characteristics: age, disease type (ALL versus LBL), immunophenotypic subtype (early T-cell precursor [ETP] versus non-ETP), complex cytogenetics, central nervous system involvement at salvage, first complete remission (CR1) duration Results We identified 82 patients, including 39% in S1, 27% in S2, and 34% in S3+. ETP subtype was present in 35% of cases, and 16% had complex cytogenetics. Salvage therapy included standard-of-care regimens in 48 patients (59%), including nelarabine-based therapy in 21 patients (26%), pediatric-inspired asparaginase-based therapy in 11 patients (13%), clofarabine-based therapy in 9 patients (11%), and investigational-based therapies in 34 patients (41%), mainly venetoclax-based (18 patients; 22%). The CR/complete remission with incomplete hematological recovery (CRi) rate was 46%, with a median duration of response of 4 months. With a median follow-up of 37 months, the median OS was 8 months, and the 2-year OS was 23%. Only 14 patients were alive in remission at their last follow-up. In multivariate analysis, earlier salvage therapy was the only predictor for better survival (hazard ratio 0.57 [95% confidence interval, 0.33-0.99], P=0.049). A 3-month landmark analysis showed a survival benefit for consolidative hematopoietic stem cell transplant (HSCT) after CR to salvage therapy (2-year OS rate of 56% versus 24%, P=0.002). Conclusions The current study highlights the continuous unmet need of patients with R/R T-cell ALL treated with contemporary standard regimens and provides a reference for future clinical trials in this population.